Integrated circuits are typically fabricated onto and within semiconductor substrates, with the continuing trend being towards ever-smaller devices and circuitry. The key to this progress has been microlithography which has been used to create micron- and submicron-scale structures for fabricating various devices of the integrated circuits. For decades, microlithography has been dominated by the use of light and photosensitive material to etch or otherwise pattern structures and regions relative to an underlying semiconductor substrate. Such is commonly referred to as photolithography, whereby the details of a particular circuit layer can be projected from a photomask onto photosensitive material on the substrate. The use of progressively shorter wavelengths of the incident radiation, along with increased complexity in the photomasks, has continually led to a reduction of the minimum feature size of the circuit devices using photolithography.
Present generation photolithography typically operates at a wavelength of 193 nanometers, which is about 8 millionths of an inch. Such can enable the patterning of structures on a substrate having a half-pitch as low as 90 nanometers. Considerably shorter nanometer wavelength light is being investigated, and coupled with other masking and projecting techniques, is expected to enable at least sub-70 nanometer photolithography. However, it remains to be seen whether the equipment enabling such photolithography will be cost prohibitive. Accordingly, needs remain in microlithography for producing ever smaller and denser integrated circuit devices.
One such potential solution is known as imprint lithography. Essentially, such is a micromolding process in which the topography of a template, or mold, defines the patterns to be created on a substrate resulting from physical contact of the template with the substrate. Typically, the template is pressed into a thin film formed onto the substrate, deforming the shape of the film according to the features of the template and forming a relief pattern in the film. The imprinted film might be further processed by projecting radiation through the mold into the film to solidify the film, followed by mold removal. Alternately, by way of example only in thermal imprint photolithography, suitable solidification of the imprinted film might occur by temperature reduction after the imprinting. Regardless, typically thereafter, the thin film is suitably processed to remove the reduced thickness portions, thereby forming a hard mask which can be utilized for etching or as an implant mask, by way of example only, relative to underlying material. The imprint templates are typically used hundreds or thousands of times in processing other substrates before defects start to occur from wear.
While the invention was motivated in addressing the above identified issues, it is in no way so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents.